The present invention relates to a liquid ejection apparatus for supplying a liquid having an adjusted hydrodynamic flow pressure to rows of liquid ejection nozzles.
An inkjet recording apparatus is known as a liquid ejection apparatus. The inkjet recording apparatus ejects ink contained in an ink cartridge from a recording head through rows of nozzles to form dots of ink on a recording medium.
JP-A-2004-142405 describes an off-carriage inkjet recording apparatus having an off-carriage ink supply. The off-carriage inkjet recording apparatus includes a pressurizing pump for generating compressed air. The pressurizing pump pressurizes an ink pack accommodated in an ink cartridge with the compressed air. The ink contained in the pressurized ink pack is supplied to a recording head through a supply passage.
The inkjet recording apparatus described in the above publication includes a plurality of valve units respectively connected to a plurality of supply passages communicating with a plurality of ink cartridges. Each ink cartridge contains ink of a different color. Each valve unit includes a diaphragm that opens when subjected to a predetermined pressure. The opening and closing of the diaphragm adjusts the hydrodynamic flow pressure of the ink. The ink having the adjusted hydrodynamic flow pressure is supplied to the recording head.
To increase the accuracy of the dots formed on a recording medium, a recent inkjet recording apparatus has a recording head including rows of nozzles for ejecting ink of the same color. However, the inkjet recording apparatus described in the above publication uses a single valve unit to supply ink having an adjusted hydrodynamic flow pressure to the nozzle rows. Thus, if the quantity of the nozzle rows in the inkjet recording apparatus of the above publication increases, it may become difficult to accurately supply each nozzle row with ink having the adjusted hydrodynamic flow pressure. For this reason, the inkjet recording apparatus described in the above publication cannot have a recording head including a plurality of nozzle rows for ejecting ink of the same color.